12 December 2011



Calorific value (CV)
The calorific value is defined as the quantity of heat liberated on the complete combustion of a unit weight or unit volume of fuel, at constant pressure and under the conditions known as “normal” of temperature and pressure (i.e. to 0°C and under a pressure of 1 .013 mbar). It is measured in units of energy per unit of the substance, usually mass, such as: kcal/kg, kJ/kg, J/mol, Btu/m³.

 Gross Calorific Value (GCV)
                  The higher calorific value (or) Gross calorific value (GCV) which supposes that the water of combustion is entirely condensed. The heat contained in this water is recovered.

Net Calorific Value (NCV):
            The lower calorific value (or) Net calorific value (NCV) which supposes that the products of combustion contain the water of combustion in the vapor state. The heat contained in this water is not recovered.
Heat Rate (HR):
The amount of heat input required per unit of power generated (kcal/kwh) for specific fuel being fired and specific site conditions. A measure of generating station thermal efficiency, generally expressed in btu per net kwh. It is computed by dividing the total btu content of fuel burned for electric generation by the resulting net kwh generation.

Dulong’s formulae for GCV calculation :

According to Dulong's formula

GCV = ((35.5 x C + 114.8 x H + 9.5 x S – 14.5 x O) x 1000)
                                         (100 x 4.1868)